Remove Nth capture from a string

remove_Nth_capture.lua

function remove_Nth_capture(str,capt,N) -- removes with adjacent punctuation marks
-- 1. if not N then N is 1
-- 2. if no captures or N is 0 or greater than the number of captures returns original string
local N = N and tonumber(N) and math.abs(math.floor(N)) -- validate N
	if not N then N = 1 end
local cntr = 0
local str_new = ''
	for w1, w2 in str:gmatch('(%w*)([%p%s%c]*)') do
	cntr = (N ~= cntr and w1 == capt or N == cntr) and cntr+1 or cntr
		if N ~= cntr then str_new = str_new..w1..w2 end
	end
return str_new, str ~= str_new -- 2nd val is boolean showing if any changes were made
end